﻿using System;
using System.Collections;
using System.Windows.Forms;

namespace WSBackup
{

    public class ListViewColumnSorter : IComparer
    {
        /// <summary>
        /// Specifies the column to be sorted
        /// </summary>
        private int ColumnToSort;

        /// <summary>
        /// Specifies the order in which to sort (i.e. 'Ascending').
        /// </summary>
        private SortOrder OrderOfSort;

        /// <summary>
        /// Case insensitive comparer object
        /// </summary>
        private CaseInsensitiveComparer ObjectCompare;

        /// <summary>
        /// Class constructor.  Initializes various elements
        /// </summary>
        public ListViewColumnSorter()
        {
            // Initialize the column to '0'
            ColumnToSort = 0;

            // Initialize the sort order to 'none'
            OrderOfSort = SortOrder.None;

            // Initialize the CaseInsensitiveComparer object
            ObjectCompare = new CaseInsensitiveComparer();
        }

        /// <summary>
        /// This method is inherited from the IComparer interface.  It compares the two objects passed using a case insensitive comparison.
        /// </summary>
        /// <param name="x">First object to be compared</param>
        /// <param name="y">Second object to be compared</param>
        /// <returns>The result of the comparison. "0" if equal, negative if 'x' is less than 'y' and positive if 'x' is greater than 'y'</returns>
        public int Compare(object x, object y)
        {
            // Cast the objects to be compared to ListViewItem objects
            var listviewX = (ListViewItem)x;
            var listviewY = (ListViewItem)y;

            var XIsDirectory = (listviewX.Tag as FileListViewItem).IsDirectory;
            var YIsDirectory = (listviewY.Tag as FileListViewItem).IsDirectory;

            if (XIsDirectory != YIsDirectory)
            {
                return XIsDirectory ? -1 : 1;
            }

            if (listviewX.SubItems[0].Text == "..")
                return -1;

            if (listviewY.SubItems[0].Text == "..")
                return 1;

            // Compare the two items
            int compareResult;

            if (listviewX.SubItems[ColumnToSort].Tag != null)
            {
                compareResult = (listviewX.SubItems[ColumnToSort].Tag as IComparable).CompareTo(listviewY.SubItems[ColumnToSort].Tag);
            }
            else
            {
                compareResult = ObjectCompare.Compare(listviewX.SubItems[ColumnToSort].Text, listviewY.SubItems[ColumnToSort].Text);
            }

            //Ak su rovnake, zotriedime podla nazvu
            if (compareResult == 0 && ColumnToSort > 0)
            {
                compareResult = ObjectCompare.Compare(listviewX.SubItems[0].Text, listviewY.SubItems[0].Text);
            }

            // Calculate correct return value based on object comparison
            switch (this.OrderOfSort)
            {
                case SortOrder.Ascending:
                    return compareResult;
                case SortOrder.Descending:
                    return -compareResult;
                default:
                    return 0;
            }
        }

        /// <summary>
        /// Gets or sets the number of the column to which to apply the sorting operation (Defaults to '0').
        /// </summary>
        public int SortColumn
        {
            set
            {
                ColumnToSort = value;
            }
            get
            {
                return ColumnToSort;
            }
        }

        /// <summary>
        /// Gets or sets the order of sorting to apply (for example, 'Ascending' or 'Descending').
        /// </summary>
        public SortOrder Order
        {
            set
            {
                OrderOfSort = value;
            }
            get
            {
                return OrderOfSort;
            }
        }
    }
}